Traditionally, a connecting rod and cap are used for connecting a piston to a crankshaft in an internal combustion engine. The connecting rod is connected to the cap using a plurality of bolts. Extremely small clearances exist between bolt locating surfaces and mating surfaces on the connecting rod and cap. During operation of the engine, the connecting rod can deflect, causing the bolt and rod to come into contact with each other. This contact and motion can cause fretting, microscopically welding the bolt and rod together where their surfaces contact. Further motion of the bolt and rod can break these welds, causing material damage such as cracking. Because connecting rod bolts are highly stressed tensile components, any cracks can propagate and cause failure of the bolt and rod.
An anti-fretting bolt is described in U.S. Pat. No. 3,455,587 (“the '587 patent”) of Gallois that issued on Jul. 15, 1969. In particular, the '587 patent describes a bolt with a bearing portion having axially-spaced circular grooves with a U-shaped cross-section defining hollow portions separated by ribs. Cracks may still form in the bolt during operation, but the cracks cannot reach stress lines of the bolt as easily as in standard bolts that do not contain the hollow portions and ribs.
While the bolt of the '587 patent may help to reduce bolt and rod failure, it may still be less than optimal. Specifically, the bolt design of the '587 patent only inhibits crack propagation, but does not prevent cracks from forming. Over time, the bolt of the '587 patent may still fail due to fretting and subsequent crack formation.
The connecting rod bolt of the present disclosure solves one or more of the problems set forth above and/or other problems with existing technologies.